The present invention relates generally to electroactive polymer devices that convert between electrical energy and mechanical energy. More particularly, the present invention relates to fluidic communication control devices and systems comprising one or more electroactive polymer transducers.
Fluid systems are ubiquitous. The automotive industry, the plumbing industry, chemical processing industry and the aerospace industry are a few examples where fluid systems are of critical importance. In fluid systems, it is often desirable to control properties of a fluid flow in the fluid system to improve a performance or efficiency of the fluid system or to control the fluid in the fluid system in manner that allows the fluid system to operate properly.
As an example, in the automotive industry, the demand for higher power, better fuel economy, and reduced emissions from automobiles calls for continued improvement of automobile components, in particular, the need for reduced size, weight, and costs of automotive components “under the hood.” Additionally, the demand for power, fuel economy and reduced emissions often results in conflicting requirements for engine performance. For example, higher power usually comes at the expense of fuel economy and/or emissions. Therefore, engine components must also have flexible operating characteristics to achieve performance at different speed ranges.
A significant number of components under the hood of an automobile serve the function of controlling fluid flow in a manner that relates to engine performance and emissions. Flow control devices are found in different parts of the engine and various engine subsystems including the fuel injection system, the air intake system, the cooling system, and the exhaust system.
For instance, the operating characteristics of the intake and exhaust valves for the combustion chamber are important to engine performance. The intake valve opens at proper times to let air/fuel mixture into the combustion chamber and the exhaust valve opens at proper times to let out the exhaust. The valve timing and lift (amount of valve opening) characteristics of an engine has a major influence on engine performance at different speed ranges. Current engines have fixed valve timing and lift so performance is a compromise between power and fuel economy. The engine performance at different speeds can be optimized by employing variable timing and valve lift. However, conventional actuator technology, such as solenoids and hydraulics, are expensive, heavy, and complex at the power levels required to actuate intake and exhaust valves. Thus, variable timing and valve lift has not been heavily utilized in the automotive industry. The limitations of conventional actuator technology, such as cost and weight, are important in many fluid control applications besides the automotive industry. For instance, weight and cost are usually critical considerations in aerospace applications.
New high-performance polymers capable of converting electrical energy to mechanical energy, and vice versa, are now available for a wide range of energy conversion applications. One class of these polymers, electroactive elastomers (also called dielectric elastomers, electroelastomers, or EPAM), is gaining wider attention. Electroactive elastomers may exhibit high energy density, stress, and electromechanical coupling efficiency. The performance of these polymers is notably increased when the polymers are prestrained in area. For example, a 10-fold to 25-fold increase in area significantly improves performance of many electroactive elastomers. Actuators and transducers produced using these materials can be significantly cheaper, lighter and have a greater operation range as compared to conventional technologies used in fluid control applications.
Thus, improved techniques for implementing these high-performance polymers in fluid control applications would be desirable.